Magnetic flexible catheter tracking system and method using digital magnetometers

Abstract

A method for magnetic tracking of a flexible catheter device or another flexible elongated device, the method comprising: receiving by a host server a plurality of sensed values of a local magnetic field, sensed by a respective plurality of sensors, wherein the host server is optionally included in a controller of the sensors, the sensors are located along a flexible tube of a device, wherein the sensed values are at least partially due to at least one alternating magnetic field generated by at least one magnetic field generator, the source amplitude and frequency of each generated magnetic field are given to the host server; and calculating by the host server, based On the sensed magnetic field values and the given source amplitude and frequency of each generated magnetic field, a localization of the flexible tube.

What is claimed is: 
     
         1 . A method for magnetic tracking of a flexible device, which is a flexible catheter device or another flexible elongated device, said flexible device comprising an elongated flexible body, the method comprising:
 a receiving by a host server a plurality of sensed values of a local magnetic field, sensed by a respective plurality of digital magnetometers, the digital magnetometers are located at corresponding multiple locations along the elongated flexible body of said flexible device, wherein the sensed values are at least partially due to at least one alternating magnetic field generated by at least one magnetic field generator; and   b. calculating by the host server, based on the sensed magnetic field values and source amplitude and frequency of each generated magnetic field, an estimation of a curve localization of said elongated flexible body;   
       wherein said calculating comprises:
 incorporating the sensed magnetic field values and source values of each generated magnetic field in a localization algorithm; 
 incorporating shape constraints of the elongated flexible body of said flexible device in the localization algorithm; and 
 performing curve optimization based on the incorporated values and said incorporated shape constraints, to determine said estimation of said curve localization of said elongated flexible body. 
 
     
     
         2 . The method according to  claim 1 , wherein the flexible device comprises a tip, and wherein the digital magnetometers are located along said flexible device, on at least one of said tip and said body of said flexible device. 
     
     
         3 . The method according to  claim 1 , wherein the localization algorithm comprises an energy function of the curve of the elongated flexible body and errors of the magnetometers, and wherein said curve optimization comprises minimization of said energy function. 
     
     
         4 . The method according to  claim 1 , wherein the host server is calibrated with initial orientations and positions of the plurality of digital magnetometers. 
     
     
         5 . The method according to  claim 1 , wherein the shape constraints include information about rigidity and/or flexibility limitations of the elongated flexible body. 
     
     
         6 . The method according to  claim 1 , wherein the shape constraints include known structural relationships between the positions and orientations of the digital magnetometers along the elongated flexible body of said flexible device. 
     
     
         7 . The method according to  claim 1 , wherein the shape constraints include approximation of the shape of the elongated flexible body as a set of line segments, each line segment connecting between two of the plurality of digital magnetometers. 
     
     
         8 . The method according to  claim 1 , wherein the shape constraints include fixed and known orientations and distances of each magnetometer relative to its adjacent magnetometers. 
     
     
         9 . The method according to  claim 1 , wherein the shape constraints further include smoothness constraints of the shape of the elongated flexible body. 
     
     
         10 . The method according to  claim 1 , wherein the localization algorithm describes the curve of the elongated flexible body with an energy function that encodes the shape constraints of the elongated flexible body. 
     
     
         11 . The method according to  claim 1 , wherein the host server is configured to fit the curve to measurements of the magnetometers, by minimizing errors of the measurements and of the curve. 
     
     
         12 . The method according to  claim 1 , wherein said digital magnetometers are digital DC magnetometers. 
     
     
         13 . The method according to  claim 1 , wherein a plurality of said digital magnetometers are located on a same digital communication bus. 
     
     
         14 . The method according to  claim 1 , wherein said calculating comprises incorporating physical distortion model in the localization algorithm, to compensate for dynamic magnetic distortions. 
     
     
         15 . A system for magnetic tracking of a flexible device, which is a flexible catheter device or another flexible elongated device, the system comprising:
 a at least one generator, each configured to generate at least one alternating magnetic field;   b. a flexible device comprising:
 i. an elongated flexible body; 
 ii. a plurality of digital magnetometers, the digital magnetometers are located at corresponding multiple locations along the elongated flexible body of said flexible device, each configured to communicate sensed values of a local magnetic field, wherein the sensed values are at least partially due to the generated magnetic field; and 
   c. a host server configured to:
 iii. receive the sensed local magnetic field values from the corresponding digital magnetometers; and 
 iv. calculate, based on the sensed magnetic field values and source amplitude and frequency of each generated magnetic field, an estimation of a curve localization of said elongated flexible body; 
 wherein said calculate comprises:
 incorporating the sensed magnetic field values and source values of each generated magnetic field in a localization algorithm; 
 incorporating shape constraints of the elongated flexible body of said flexible device in the localization algorithm; and 
 performing curve optimization based on the incorporated values and said incorporated shape constraints, to determine said estimation of said curve localization of said elongated flexible body. 
 
   
     
     
         16 . The system according to  claim 15 , wherein the flexible device comprises a tip, and wherein the digital magnetometers are located along said flexible device, on at least one of said tip and said body of said flexible device. 
     
     
         17 . The system according to  claim 15 , wherein the localization algorithm comprises an energy function of the curve of the elongated flexible body and errors of the magnetometers, and wherein said curve optimization comprises minimization of said energy function. 
     
     
         18 . The system according to  claim 15 , wherein the device further comprises a flexible PCB along the flexible device, wherein the digital magnetometers are located along the flexible PCB. 
     
     
         19 . The system according to  claim 18 , wherein the flexible PCB is wrapped in a helix manner on a wall of the flexible device. 
     
     
         20 . The system according to  claim 15 , wherein the device further comprises a communication bus configured to carry the sensed values data digitally from the plurality of digital magnetometers towards the server. 
     
     
         21 . The system according to  claim 20 , wherein the communication bus includes up to four wire lines that may carry the sensed values digital data from and provide power to the plurality of digital magnetometers. 
     
     
         22 . The system according to  claim 15 , wherein a plurality of the magnetometers are installed on a same flexible printed circuit. 
     
     
         23 . The system according to  claim 22 , wherein the flexible printed circuit includes thinner portions between the digital magnetometers. 
     
     
         24 . The system according to  claim 15 , wherein a plurality of said digital magnetometers are located on a same digital communication bus. 
     
     
         25 . The system according to  claim 15 , wherein the at least one generator comprises one or more transmitting coils which generate EM fields of different geometry. 
     
     
         26 . The system according to  claim 15 , wherein said digital magnetometers are digital DC magnetometers.